1. Field of the Invention
The present disclosure relates to an electric power controlling apparatus having a control unit that controls input/output information of each electric power source in a state where a plurality of electric power sources are connected in parallel and a method for controlling the electric power.
2. Description of the Related Art
FIG. 1 is a block diagram of a prior art system using a power source.
As shown in FIG. 1, a system includes a central process unit (CPU) 14, a power source 10, and a display unit such as a liquid crystal display (LCD) device 16, and a sub-control unit such as a microcomputer 15 that is coupled to the power source 10 and the LCD device 16 to control data or signals.
The power source 10 includes a charger 13 capable of charging an alternative current power source 11 and sub-power sources such as cells 13a. 
Meanwhile, in FIG. 1, the cell 13a that is the sub-power source is exemplarily integrated in the charger 13 to illustrate that the cell 13a is charged in or through the charger 13. However, the cell 13a may be provided independent from the charge.
FIG. 2 is a block diagram of a power source unit 100 having a plurality of cells that are connected in parallel and applying electric power to a system.
As shown in FIG. 2, a plurality of cells 21 and 22 are connected in parallel. A system 25 is driven by the cells 21 and 22. A protecting unit 24 is coupled to the cells 21 and 22 and the system to protect them. A charging/discharging switch 23 is provided to charge and discharge the cells 21 and 22.
In the above-described structure, only one cell having a large capacity or two or more cells that are connected in parallel are used to increase an operation time of the sub-power source in the system (e.g., a portable electronic device).
When two or more cells are connected in parallel to increase the operation time, currents applied to the respective cells may be different due to an impedance difference during charging or discharging.
That is, as the end of the discharging, one of the cells has a large discharging current to operate the protecting unit 24 and another cell is in a state where the discharging is finished.
In addition, due to the difficulty in an impedance matching in the cells and a loop path difference of the cells that are connected in parallel, some cells may be functionally deteriorated.
Further, when there is a short circuit in a specific cell in a state where the cells are connected in parallel, a relatively large current is concentrated. This may cause the explosion and fire of the system.
Even when only one of the cells that are connected in parallel malfunctions, all of the cells cannot be used.
In order to solve the limitations, the protecting unit 24 such as a positive temperature coefficient (PTC), a temperature compensation circuit, or an additional circuit is necessary for each of the cells.
Accordingly, it is not recommended to use the cells that are connected in parallel due to the additional use of the protecting units.